Holy anger is righteous because it does not affect rebirth in the Pure Land.
Suppose at service a heckler curses the priest loudly and disturbs the wa, the harmony during chanting of the Twelve Adorations.
Holy anger is when the priest stops the service and asks the heckler to leave immediately.
That kind of anger is warranted because a temple is for dharma practice, and hecklers are unwanted.
Though it is best that a member of the temple ask the heckler to leave first, because if the priest has to intervene then he'll need to calm down before carrying on with the service.
Holy anger does not affect rebirth.
Even if it is evil passion, because such anger is used to ask a heckler to begone or to awaken a napping member of the temple, it is justifiable.
As long as the priest or member does not curse or use violence, no harm or evil karma results.
Thus it is excusable, this holy anger.